46 replies to this topic

[Carlos W]

 

Is  this anything to do with the OPs original question, or has it turned into a bit of one upmanship?

 

 

Can we keep things on topic please?

 

It is pertinent, because the OP was losing oil, and that could be down to valve guides as much as bore wear.

 

But you 2 bickering amongst yourselves when neither of you are going to back down is getting no-one anywhere

[MRA]

Fair enough.

Edited by MRA, 23 February 2016 - 12:39 PM.

[Steve220]

Are those Pistons only 2k miles old? With those marks, my money is on bore wear. Who did your fueling?

[Dusky]

Are those Pistons only 2k miles old? With those marks, my money is on bore wear. Who did your fueling?

When you google bore wash on google images you get a lot of similar images, think you're on the right track ^^

[Steve220]

Sorry, I meant bore wash lol.

Just to give you guys some insight, I rebuilt a rover T16 a few years back and the engine was showing classic signs of over fuelling when I picked it up (constant smell of petrol, black smoke on boost). I discovered once home the fuel pressure regulator was set to 4bar (usually 3). It burnt masses of oil constantly. On stripping I found this.

Edited by Steve220, 23 February 2016 - 12:07 PM.

[MRA]

That can also be the symptoms of not allowing the engine to warm up thoroughly before a good thrashing, ie aluminium heats up quicker than cast iron and as such expands thus picking up on the bore.

 

I would concur that this is more likely to be bore wash, looking at the amount of carbon deposits around the ring lands...

Edited by MRA, 23 February 2016 - 12:38 PM.

[Steve220]

You get more of a skirt wear with that though. My machinist has a chart on the wall which, in hind site, I wish I'd taken a photo or copy of. It was a really good diagnostic of piston wear.

[minivanman8]

Are those Pistons only 2k miles old? With those marks, my money is on bore wear. Who did your fueling?

2-3k.

 

Took it to local machine shop today to get some accurate measurements and they said it looks like dirty oil, possible from the diff (Minispares 4 pin).

 

Fuelling done by max on RR - I trust his work.

 

I have facet fuel pump fitted and was advised that no fuel pressure regulator is needed. Now I'm not so sure!?

[minivanman8]

That can also be the symptoms of not allowing the engine to warm up thoroughly before a good thrashing, ie aluminium heats up quicker than cast iron and as such expands thus picking up on the bore.

 

I would concur that this is more likely to be bore wash, looking at the amount of carbon deposits around the ring lands...

 

Not guilty your honour. I always let it warm up thoroughly before a good thrashing (except the very last journey, but by this time it was burning a ton of oil and it was only a 2 minute drive).

 

Just to clarify - that's Steve's picture as an example, not from my engine. My piston is at top of page 2.

[MRA]

 

That can also be the symptoms of not allowing the engine to warm up thoroughly before a good thrashing, ie aluminium heats up quicker than cast iron and as such expands thus picking up on the bore.

 

I would concur that this is more likely to be bore wash, looking at the amount of carbon deposits around the ring lands...

 

Not guilty your honour. I always let it warm up thoroughly before a good thrashing (except the very last journey, but by this time it was burning a ton of oil and it was only a 2 minute drive).

 

Just to clarify - that's Steve's picture as an example, not from my engine. My piston is at top of page 2.

 

 

Sorry mate, didn't mean to sound like I was accusing you of thrashing.... I was just "ticking" things off the list

[MRA]

 

Are those Pistons only 2k miles old? With those marks, my money is on bore wear. Who did your fueling?

2-3k.

 

Took it to local machine shop today to get some accurate measurements and they said it looks like dirty oil, possible from the diff (Minispares 4 pin).

 

Fuelling done by max on RR - I trust his work.

 

I have facet fuel pump fitted and was advised that no fuel pressure regulator is needed. Now I'm not so sure!?

 

Really ?   dirty oil from a 4 pin diff ?  the amount that it could possibly hold would be negligeable and certainly not to blame.

 

Facet fuel pumps if I am not mistaken fun at about 5 to 6 psi which is too high for a N/A SU carburettor.

 

check the baulk ring friction surfaces for loss of the coating as this is exceptionally hard and can easily "fall apart" and then float around in your oil.

 

Do you still have the oil you drained out of it ?

[GraemeC]

Many of the Facet solid state (cube) and Posiflow pumps max out at 4psi (some less).

I run one of these without a reg and have no issues on a HIF44.

[Dusky]

Facet cubes have different psi ratings, im using the fast road one I think, without any problems, been on a 998 with stage one up to my 1330, all without problems.

[Cooperman]

In a nutshell, it looks like inaccurate original machining possibly combined with an over-rich mixture.

For the person who assembled the engine the clue should have been in the excessive ring gaps at the time of the 'trial-build', assuming a trial-build was done (and there's a thing).

Now it is decision time. Are you prepared to re-use those (expensive) pistons and either sleeve the existing bores, or get an un-re-bored block (not easy to find) to take to 1293, or do a complete re-build re-boring to the next size up and increasing the chamber volume to cater for new pistons with a smaller dish volume? You could reduce the boost pressure to keep the C.R. within sensible limits and re-curve the distributor to suit.

[MRA]

Reduce boost ?  what is this thing you talk of ???